Regenerative coke oven and method of operating the same



Sept. 20, 1932. H. E MITCHELL 1,878,972

REGENERATIVE COKE ovEN' AND METHOD oF OPERATING THE SAME Filed Deo. 2, 1926 5 sheets-sheet' 1 A 7TORNEKS` Sept. 20, 1932. H. E. MITCHELL 1,878,972

REGENERATIVE COKE OVEN AND METHOD OF OPERATING THE SAME Filed Deo` 2, 1926 3 Sheets-Sheet 2 I bq.

n A TTUHNEYS Sept. 20, 1932. H. E. MITCHELL REGENERATIVE COKE OVEN AND METHOD OF OPERATING THE SAME Filed Dec. 2, 1926 3 Sheets-Sheet 5 INVENTOI? f/ENEY BY ,nk-MMM A non/vus Patented Sept. 20, lQZilZ A renauuarrsn srarssiaajrsnr orties HENRY EARL METCHELL, OF BUFFALO, NFV YORK, ASSIGNOR TO SEMET-SOLVAY COMPANY, OF NElF YORK, N'. Y., A OORPORATON 0F NEW YORK i Y `v REGENERATIVE COKE OVEN .AND METHODy OF OPERA'ING THE SAME Application filed December 2, 1926. Serial No. 152,103.

The object of the invention is to establish an air feed which will furnish the requisite air to the separate heating fines in more ade-.

quate amounts and in more uniform volume per flue than has heretofore been possible and to accomplish this object in a most economical and in a. substantially automatic way. Une result of the invention is o enable a greater number of ovens to be operated in conjunction with a single air system than was heretofore possible. Another result is that with a given battery the production will be increased since the ovens will complete their functions in a materiallyl shorter time than heretofore, These and other advantages which will be referred to during the course of this specification will be obvious to those skilled in the art.

Heretofore, it has generally been deemed necessary to rely upon power driven means to propel the air to theinlet of the several heating flue systems. The airwas consequently drawn in at one end of the oven battery and forced by fans or blowers to the other end `(which was closed). lilith such a system it is obvious that the capacity of the fan controlled the capacity of the battery of ovens because the battery could not be ein tended beyond the distance to which the forced air draft penetrated. rlhis limited the number of colring ovens which could maire upA abattery of such ovens. Even when the number of lovens was duly limited, the supply of air was non-uniform and the ovens most remote from the blower received a differently modulated air supl ly than the other ovens in the seiies. Y Y u JAccording to the present invention the fan or blower may be dispensed with and instead thereof an air passage freely open to theatmosphere at both ends of the battery (i. e. having ports located on opposite sides of the `fully and uniformly. The chimney draft which removes the wastefproducts of combustion from the heating yflues of' all of the ovens is relatively uniform in its'l action on the flues ofthe severalovens as contrasted with the marked differential effect of a fan,

and, consequently, when the chimney draft is relied on as the sole force for establishing circulation through the heating flues of the entire battery system and said flues are all in communication attheirair admission inlets with a plentifulsupply ofair free .from an artificially applied pressure, the whole battery of ovens lwill functionkmore uniformly and more efciently.` V Y ln accordaifice with my invention l provide ahy-product coke oven battery having long airandwaste gastunnels4 with an air supply system having aiplurality of airports incorporated therein at various positionsv so as to supply anadequate amount of air to supportv combustion of vfuelin each of the heating flues of each oven and to cause distribution ofthe said air supply in such a manner that the proper amount of air flows to each heating flue no matter Where the flue is located in the ovenbattery. -By incorporating these featuresfin aV coke ovenstructure, l am able not only to operateV said structure to better effect, more economically, iuiiformlyfand speedily., but l am able lto operate successfully a battery comprising a greater number of ovens than one whichhas' limits imposed thereon by the` use of a fan ata sole central intake.v

y li/ly invention will be best understood by aV description of an illustrative and 'typical eX- ample talren in conjunctionwith ythe. accompaiiyingdrawings, in'wliich: Figl shows a sectional view transverse to coke ovens em-v bodying my invention and taken on the line 1-1 of F ig. 2; Fig. 2 isa sectional view taken on `line Q-Zof Fig. l; Fig-'.3 is a sectional view taken on kthe line 3-3- of Figi; and Fig. 4 shows an elevational view, partly in section, on line 4 4 of Fig. 1, of the right hand side of the battery of coke ovens shown -in the drawings.

In the drawings the letter S designates coking ovens which are arranged parallel to each other between bulkheads T so as to constitute a battery of coke ovens. Interposed between adjacent ovens is a division wall U which gives rigidity to the structure; A system of heating flues V, herein depicted as horizontal zigzag flues, are positioned in the usual manner betweenthe sides of each oven and the nitely separates the main passages or tunnels N and O, while the main passagesy N and O are themselves divided by apertured partitions Y to delineauxiliary passages` N and O. A plurality of spaced apertures A (see Fig. 2) may be so spaced and varied in size as to secure'a uniform and adequate air supply throughout the main passages N and O. Adits whereby atmospheric air may enter the auxiliary passages Nand O are provided at their ends (i. e. on opposite sides of the trans-V verse median line ofsaid'auxiliary passages).

In the drawings these adits at one end of the auxiliary passages, are indicated by the valve ports G and K. vAt the other end,`the aditsV for air to the auxiliary passages are formed .by the spaces between the ends of the partition walls Y and the end wall of the oven. The main passages are in communication via channels Q, and R with a commonstack flue Z which leads to a stack or chimney P.

In order to control the communication be-V tween passage or tunnel N and flue Z and the communication between passage or tunnel O and flue Z, a main damper A is vinterposed between the former members and a Vmain damper B between the latter members. These dampers are connected together by any suitable means such as 'a Vcable 1 whichvmakes a frictional contact with idler pulleys 2 and-a driving pulley 3. When one damper is in a raised position, as damper A in the drawings, a communication is lestablished between one of the gas passages, {such as N and `the stack flue Z. The draft or suction ofthe chimney. P sucks the valves or doors C and D inwardly to close ports G and H, and thusl to close the Y main andauxiliary passages N and N respectively, to the atmosphere. I-Iotv waste product'sof combustion from the'r'egenerators Y above passages yN and N passthrough theseA passages and then go to the chimney. SimuL taneously, air is sucked inthrough passages O and O via ports J and K respectively due to the fact that valves or doors E and F are operatively connected to doors D and C respectively and are open to the atmosphere when doors D and C are closed. These doors may be connected in any appropriate manner such as with cables 5 running in pulleys 6, each of the latter being supported by a. combination door stop and bracket 7. The door stop holds each doorkor valve at a suckable angle so' that each door lmay be drawn in quickly and tightly when subjected to the suction of the chimney. In this connection it sponding damper is opened, while the closed' valves are under a static pressure.

At the other end of the battery of oven adjacent to the stack, I provide air ports L and M which may be closed by a slide valve 8.k

This valve slides in guides 9 positioned at each side thereof and has a` rack 10 secured to itsl upper surface. A pinion 11 keyed to shaft 12 coacts with rack 10 and causes the,

latter and the associated valve 8 to move back and forth. The shaft 12 may be supported in any customary manner and is rotated by a sprocket gear 13 securedl thereto which is driven by a chain 14 and a drivingv sprocket gear 15. `When the driving pulley 3 rotates in one direction it raises damper A from a closed position to an open position, as herein illustrated. Driving sprocket gear 15 rotateswith pulley 3 and drives sprocket gear 13 through the medium of chain 14. Pinion 11 being geared to the same shaft as sprocket gear 13 rotates therewith and moves valve 8 from air port'M to L by its coactions with rack 10. In the aforesaid manner the operation of the main driving gear 3 by Vwell known automatic means (not'shown) not only oper-v Simultaneously, air port M is opened and airv ports J and K are likewiseopened. By the reversal of the gas flow, main damper B is raised, air port MV is closed by the rack and pinion mechanism, and air ports J and K are closed byy valves E andl F respectively which are sucked in Yby the draft or suction of the chimney. When these operations. occur .air portsL, G, and H are opened simultaneouslyv and `automatically with the; closingY of the other set of air ports.

ovens in accordance with my inventionor a battery of ovens' having my improved air control means incorporatedl therein is. readily obvious/coone'slrilledin the art. The colring chambers are charged and sealed in the usual manner. Air is admitted simultaneously `at each. end ofthe battery of coke. ovens. tothe long gas passages asindicated by the arrows Y in passages O, O (Figs. 1l and 2)v and thence ing air is preheated. VThe frictional resistance to the Howing air is reduced substantially because the air path onlyextends from one of, whereas heretofore the air pathl extended from one end of thel battery to the otherend thereof. Due to these relatively short air.

paths and to the absence of unevenly applied. pressure, there is a substantially even distribution of air to all of the -regenerator units.

The preheated air from the regenerators Hows to the heating Hues in the usual manner,- wherein the said air supports combustionof;

the fuel admitted from burners positioned in the Hue system, The productsof combustion resulting from the burning of the fuel pass through the heating Hues into another set of regeneratorswhich abstract heat from the hot waste gases before the latter passfasa common stream to the chimney as indicated'y by the arrows inpassages N, N- (Fig, 2),

At the termination ofa period the gas-Howiereversed in a well-known manner'.v now Hows to the second set` of regeneratorswhich 0 were heated bythe hot-products ofcombus.y tion of the prior period. The portsthrough which the 4air enters the batteryto the second set ofregenerators are likewisey positioned at air Hows from each endtowardthe middle of the battery. The preheated air? Howing from the regeneratorssupports combustion ofi the. fuel in the heating Hues, and theresulting.

ports, are closed by the. suction ofthe Starck." Underfcertain conditions, however, the valves;

onall theair ports ateachelnd: of thebattery4 may-be Operated by the, YStgt/i911,Qj the StCkf Y for instance, in the embodiments illustrated in thedrawings, valves controlling air ports L andM maybe pneumatically operated 'as 5 well as air ports Gr, H, I, and-"KJ The ain.

The method of operating.; by-product, coke,

to the regeneratorsk wherein the coldincomend of the battery to about the middle thereeach end of the battery so that theincoming products of combustion-flow asa common,v

ports M5,v J, and'K related to damper B. are opened Simultaneously and automatically with the. closing ofthe otherv set of air; ports; G, H, andL. In other words, the air ports connected: toone set of gas passages (for instance O and 0f) are arranged to` admit ainto. their respective Hueswhen the related maindamper (for instance B). is setto closethe communication between the set of passages and the stack Hue, whereas the air portsl connectedto. the other set. of passages being arranged to shut 0H the airto their respective Hues when their.- related damper is set to open thecommunication between the last setof passagesand the chimney. `This; arrangementprovidesa very effective method of controlling.Y the How ofcoldair. to the regenerators. andthe How4 of hot waste products of v combustion tothe stack, aswell as reversing ,oralternating the gas Howthrough thegas' circulationzsystem of the battery of ovens.

, It wil-'l'kbenotedi that my invention. providesV meanswhichcan be easily incorporated in existing-byproduct coke oven batteries with-A out substantial changes. Coke oven batteries which have been provided with myairv control. mechcanism operate without the use), ofi air fans andproduce more` coke andv byproducts per week-or month than heretofore,

i. e. `the number, of ovens pushed. pertime unit fromeach battery has been increased.

, It will be `further observed that when my invention is embodied in a new battery of' by-product coke ovens agreater number of ovens may be-incorporated in abattery under the sa-me conditions than formerly" or a greaternumber .of ovens can be pushed: perlweek ormonth from a. battery-containing the same number of ovens'as inl-structures ofthe prior. art. Y Y

' Furthermore,wh'en a battery ofr by-product cokeovenszisoperated in accordance with my invention, a relatively flexible s stem of production is available. This exibility which permits operating the ovens at higher tlianratedv capacity without the use of exces-l sivequantitiesoffuel gas and without loss of by-products'is due in large part to the more uniform lheatingth'rougliout theV oven battery occasioned by the more even distribution ofthe air.

AlthoughA I have shown certain types of valves, operating-mechanism, etc., it is obvious that various.modificationsfmay be made withoutV departing from thescope and spirit of the; invention.

. I claim:4

vl'. In. a. battery-of by-product coke ovens comprisinga seriesof alternatecoking chambers4 and heating-walls therefor. arranged side byside', eachofsaid heating walls comprising heating` Hues and regenerator sets. ini communicationwithsaid heating Hues, that improvementfwhichcomprises air passages extending from.` one endf ofthe 4battery to thek other end of the battery,I and communicating with each; setof regenerators, sets of airports inthewalls. at the opposite ends-of said-*passages communicating therewith;y and meansV opera. tively associatedwith 'each ofisaid sets ofair ports to put thelatter in or. out of'eommuni-A cation with the air, each ofsaid `passages bes:V ing adaptedto be simultaneouslyopened orf closed tothe air at opposite ends of the battery. 4 1., Y; 2. In a-.battery ofby-product coke ovens comprisingaseries of alternate `colring cham-..

bers and heating wallsthereorarranged side by side, each of said heating wall'sfcomprising Tl heating lues and regenerators in communicaflue: joining the-two maini` gasxpassages Ywith awstacli, that improvement which. comprises a wall atIone end of the,.batteryhaving air' ports4 coinmunicably; connected to said main. gas passages adj aeent the stackflue, means operatively associatedwith theports whereby theport Yof one of the main gas passages may be put-into communication withthev air and the portof the other main gas'passages may besimultaneously closed to theair, said bat.-V tery having an air port connected to each gas passagein the wall at `the .other end offthe battery, and means controlling the lsecond mentionedl set ofair ports whereby the por-ts connected Withone pair Vof gas passages may` be put into communication with the air when the ports connected with the other pair of gas ,passages are .closed to 'theV air, each-'ofsaid main gas passages beinggadapted togbesimultaneously opened .or closedfto the .air at opposite ends 'of the battery." .5 I 3'. In a batteryfof by-.produ'ct'coke ovens comprising, a seriesv of alternate `coking chambers and heatingwalls thereforiarranged side by sidefeach ofsaid heating .walls comprising heating fluesand regeneratorsets in cem-L municationwith saidvheating fines, and having gas passages extending (under: 'the battery from one end toa stack flue at the. other end and communicably connected ,with the regenf erators, :said battery having air portsin the walls ofsaid passages at Ithe endszo the bat.- tery communicating with said-passages, ;a main damper in each gas passage adjacent to said stack uefor controlling 'the' communil cation .between said passagesand. the stack flue, valve'means for the. airjports,lmeans controlled byf the dampeis fwhereby the port connected toxone *gasy passageadjacent to said stack lue'maybeputinto'communie eation'with the air when -thedamper'insaid passage closes the communication between said passage and the stacli'iiue, and simultaneouslyzlwiththeaforesaid operations. the other main vdamper establishes the vcommunication between the other gaspassage and cokel ovens, .comprising aseries of alternate coking chambers; and heating walls therefor` arrangedlaterally ofeachother. in a row, eachofy said heatingwalls comprising combustion; luesyingcombination, a stack, two sets of, gasl passages extending from one end ofsaid battery-to the other,feach ofsaid sets comprising a mainggasfpassage and an auxiliaryy gas passage communicating therewith,.the main gaspassagesbeing communicably yconnected to the: `iues,V ai `stack flue joining said main gas passages with 'said-stack, afmainl damper; for cntrollingandalternating the flow or" gas froin saidsets of gas-passagesfto saidstack, and air ports'inthe walls osa-id battery for cominunicably connectingfeach `of said sets ofvpassages `with the Natmosphere, the ports connected to onel of .said main-gas passages being Varranged to admitair through both ends of .the same to v flues;communicablyconnectedftherewith when the main damper is set to close the communication. betweenthe. main Vgasi passage and the stackflue, they ports conjnectedto ,thevother main gas passage being arranged `to shut o theair totheflues communicably connected therewith ,whenl theV in'aingdainper is settoopenthe communica. tion between saidjother main gaspassageV and thestajck flue. Y n* j 5 -5. Y, *Int a battery. of regenerative by-product cokenvens, comprising a series: of alternate coking chambers; and ,heating walljs'th'e'refor7 arrangedlaterallyzof each other inarow, each oi said heating wallscomprising, combustion lues,fin combination, a stack, .two sets of. gas passagesfeXtending from oneend of said batterytogthe other, each said' sets. comprisinga main gas.v passage. and `l anauxiliary gas passage communicatingtherewith, the main gas passages being .communicablyconnected vto the hues, a stack flueY joining said main gas passages with saidrfsta'ckg; .a damper` individuallto-each of said? main zgas passages fory controlling f and .alternating the flow of gasf'rom saidfjsetsfof'gas passages to s aid stack,= 'air yp'ofr'tsinthel walls of said battery.; Efor communicably 'connecting each of -said passages with the atmos'phe r.e,` the ports connected toj' one of said main "gas passages v being 'arranged-fte air through both ends ofthe ysaine to .the fluesVv 'communicably connected therewith when the ldamper. individ-` ual, thereto .isf set {'Qlo'se the communication betweentheaforementionedqojne of said main gas passagesy and thestacl:` flue, theports convu'nected'tothe other main gas passage being arranged to shut off the air to the lues comcommunication between said other main gas ,passageand the staclrflue, and means operatively connecting thel dampers and the air ports so that when one damper closes the :communication between one of said main gas passages'and the stack flue, the other damper simultaneously establishes the communication between the other main gas passage and the stack Hue and the air ports connected to the aforementioned one of said main gas passage and' to the .auxiliary gas passage communicating therewith are adapted to be put into communication with the asmosphere, whereas the air ports connected to the other main gas passage and to the auxiliary gas passage communicating therewith are adapted to be simultaneously vput out of communication with the atmosphere.

6. In a battery of regenerative by-product coke' ovens comprising a series of alternate coking chambers and heating walls therefor,

arranged laterally of each other in a row,

eachof said heating walls comprising combustion flues, 1n combination, a stack, two sets of gas passages extending from one end of said battery tothe other, each of said setscomprisingl a main Vgas passage and an auX- iliary gas passage communicating therewith, the main gas passages being communicably connected to the flues, a stack iue joining said main gas Vpassages with said stack, a damper individual. to each of said main gas passages for controlling and alterna-ting the flow of gas from said sets of gas passages to said stack, air ports in the walls of said battery for communicably connecting each Vof said passages with the atmosphere, the ports Vconnected to one of said main gas passages being arranged to admit air through both ends of the same to the flues communicably connected therewith when the damper individualthereto is set to close the communication between the aforementioned one of said main gas passages and the stack flues,

f means connecting the dampers to 'eac-h other so that when one is in a closed position the other is in an open position,'a reciprocating valve controlling the air ports at one end of the' battery, 'and means 'operated bythe movement of said dampers for actuating said reciprocating valve.

7. In the method of operating a regenerative battery of by-product coke ovens comprising afseries of alternate'coking chambers and heating walls therefor arranged laterally of each other in a row, each of said heating walls having-horizontal heating lues incorporated therein, regen-erators communicablyconnected withthe heating flues and gas passages communicably connected with the regenerators, each passage extending Vunder the'battery from one end to the other, the steps-which comprise burning fuel in the heating flues and simultaneously admitting air to some of the regenerators through the gas passages from each'v end of the battery to support combustion of the fuel in the heating iues.L v

8. The methodof operating a regenerative battery of by-product cokeovens involving a series of alternate colring chambers and heating wallsv therefor arranged laterally of each other in a row, each of said heating walls comprisingcombustion flues, regenerators communicably connected with the. combustion flues, gas passages, each of which extends from one end Vof the battery to the other end `and is communicably connected the walls of the gasl passages having 'ports for the admission of air thereinto which com- Vof air and waste gas passages therebeneath connected for alternate supply of air tothe regenerators for feeding the heating vflues and removal of waste -gas' from the regenerators, each of said pairs comprising al vwith the regenerators and with a stack flue,

main gas'passage andan auxiliary gas passage communicating therewith, said battery having an air openingin the walls of each of the-main gas passagesY communicating therewith at one vvend of the battery, an air port in a wall of each ofthe main gas passages and the auxiliary gas passages communicating therewith Vat the other end of the battery, a door for each of the air ports, a member joining the-doors to cause the doors for thev air ports of one pair of passages to be closed while holding the doors for the air ports` of the other pair of passages open, a mechanism for alternately opening and closing each air opening, a stack and a mechanism for putting one pair of passages in Y communication with the stack 'and for creating a suction alternately in said pairs of passages suiiicient to close the doors for the air ports in one pair of passages while holding the doors for the air ports in the other pair of passages'open.

10. In a regenerative battery of coke ovens comprising a series lof alternate coking chambers and heating walls therefor arranged laterally of each other in a row, each of said heating walls being provided with heating l Yfio `lines, regenerators in communication with o the heating iiues, a main air passage extending from one' end lof the batteryto the other and air ducts'y communicably lconnecting the 5 regenerators with .said-mainair passage, said battery having a plurality of ports in the Walls thereof spaced from each other, each` 1 in communication withthe main airpassage -and with the atmosphere, said 'portsV being located' respectively-on oppositev sides of 'the transverse median r line'l of the main air Apassage. f I, o f f .11.' In a battery of vby-product coke ovens comprising a series of alternatecoking chambers 'and heating walls therefor 'arranged laterally'of each other ina row, each of' said .heating .-wallsfbeing provided with heating iiues, regenerators in. communication with 'the heating flues, Va main air passage communicably connec-ted'with the regenerators, o said battery having a plurality 'of ports in 'the wallsn thereof spaced froineach other, each 'in open communication' with the main air passage and with the atmosphere, said ports being located on opposite sides ofthe transversefmedian line of sai'd main airpaso 'sage so asto admit atmospheric` air -separately through said spaced portson oppo- -Y site sides of the transverse medianline 'to air' to said auxiliary air passage.

'12. In abattery of regenerative by-product coke ovens-embodying the combination set 'forth in claim 9, in which the doorsffor the air ports are adapted to be closedby the stack 'suc ien and in which means is provided for 'causing the "doors in their return movement toward an open position to bestopped in a Vposition inwhich they are :responsive to the -ternate coking chambers and heatingV walls closing effect of said stack suctionon subsevquent reversal of gas flow through the battery.

18. The method of operating a battery of byproduct coke ovens'having'aseries of alternate' coking chambers Vand heating walls therefor arranged laterally of each other in 'a row, each Yof said heating walls compris- Ving heating flues, which method comprises f burning fuel in the heating flues, alternately feeding air from one of two paths to the heating iiues while sending'produets of com- "bustion' from the heating flues through the Y other of said two pathsrand supplying each "of said'rpaths' withV atmospherieair at each of its ends during every' period of air flow `-thereinto. f

'414. Themethod of operating a battery of -Vlby-p'roduct'cole ovens, having'a series of al- Y, terna-te colring chambers and 'heating wwalls 5' therefor arranged' laterallyjoffeachV other lin the main air passage in'the'neighborhood of a row, each of said heatingwalls comprising heating flues anda chimney for the battery, which method comprises burningfuel in theV heating flues, leading hot products of combustion of the fuel in the heating'flues fromwo each separate' set of the flues into a common stream and thence Vcausing said stream,y to flow to the chimney,'periodically-leading the hot products of combustion from each sepaf rate set of sa-idrflues into a second independ--57 5 ent common stream, and always establishing free communication with the atmosphere for incoming air at both'ends of the path defined by thatone ofthe two aforesaid common streams which is not being traversed by 550 the hot products of combustion, and feeding f air' from said path to -the heating flues.

products ofcombustion o'f the fuelvinthe heating flues to independentheat absorbers, then Aleading the yproducts ofcombustion from each of such absorbers into a common stream, and thence causing said stream to ow to theC chimney, periodically transferring heat from the hot products Vof combustion to a second set of heat absorbers and leading the resultant 'v products of'c'ombustion from each of saidab- 'sorbers into a second common stream' andfIOO theneecai'ising' said stream to flow to the chimney, and always establishing free communication with the atmosphere for incoming air at both ends of the path defined by that one of thetwo aforesaid common streams whichClOS is not being traversed bythe products of combustion, and, feeding airfrom said path to the' heating fines. Y

16. The method of operating a battery of by-product co'ke ovens, having a series of al-Ello therefor arranged laterally of eachV other in a-row, each of said heating walls comprising heating iiues and a chimney fer the battery, whiehmethod comprises burning fuel in the1`115 heating flues, leading hot products of coini bustion of the fuel in the -heating flues from each separateset of the iiues into a common stream and thence causing said stream to How to the chimney, periodically leading the hot` products of combustionV from each separate set of the fines into a second independent common stream, and always establishing free communicationwith the atmosphere for ineoming air atboth vends ofthe path defined'i125 yby that one of the two aforesaid common vstreams Vwhich isr not being traversed by the hot products of combustion, and feeding air from said path to the heating iiues, establishing-achimney` suction and causing said suc-V tion to impart the movement of the gas flow involved in the conduct of the aforesaid steps.

17. In a battery of by-product coke ovens having a series of alternate coking chambers and heating Walls therefor arranged side by side, each of said heating Walls comprising Y heating tlues, regenerators in communication with the heating lues, a main air passage communicably connected With the regenerators and battery Walls having a plurality of ports spaced Jfrom each other, each port being in communication With the main air passage and With the atmosphere, said ports being so located as to admit atmospheric air through said spaced ports to the main air passage in the neighborhood of at least each of the two ends of said main air passage.

18. In a battery of by-product coke ovens having a series of alternate coking chambers and heating Walls therefor arranged side by side, each of said heating Walls comprising heating fines, an air passage extending from one end of the battery to the other end, ports located in the Walls of said passage so as to admit atmospheric airA thereto adjacent the two ends thereof and regenerator sets in communication with said air passage and said heating lues. n

In testimony whereof I have hereunto set my hand.

HENRY EARL MITCHELL. 

